Sing-along entertainment, such as Karaoke, is a popular pastime around the world. However, as any attendee of a Karaoke event can attest, a singer's enthusiasm may be far greater than their singing talent. One common shortcoming of amateur (and occasionally professional) singers is being off-key.
Even if a singer is only slightly off-key (or off-pitch), this can cause the performance to be much less enjoyable both for the singer and the audience. Any ability to help correct the singer's vocals would vastly improve the performance and the enjoyment of all parties. More people would be willing to participate if they knew they would not be embarrassed by their potentially off-key singing.
Another problem is that while a singer may be close enough in pitch through much of a song, certain notes may simply be beyond their range. Therefore a singer may greatly benefit from just a few “adjustments” to turn a mediocre performance into a great performance.
Another problem with Karaoke is the need to prepare materials in advance of the performance. Music which does not include the lead vocal must be prepared and provided to the singer. Many music industries prepare such vocal-free music, however a performance may be limited by the lack of recorded music without removed lead vocals.